Rimember

Rimember is a useful app to improve your general knowledge. From time to time you come across things that you want to remember and that you memorize at the time but after a certain time you tend to forget.
Rimember can help you save such things at one place and periodically remind you via notifications so that you never forget them.
For example, let's say you want to remember that first CEO of Apple was Steve Jobs. So you open Rimember, save it in there and forget about it. You save many such things that you want to remember in the app.
Now, every day Rimember will send you a notification of one of your saved things. So say, on 1st May you were reminded that first CEO of Apple was Steve Jobs. In a few days you forgot that, then, on say 20th June you were reminded again of the same thing. Eventually you'd have it memorized simply because you've seen it too many times. At that time you can reduce the notification frequency of this particular item and continue being reminded of other such things that you want to remember.
This way you get to relearn one of your saved facts every day. Hardly 5 seconds that you spend in reading the notification will be a useful investment into improving your knowledge of useful facts.
Do make that investment.